Aspects of the present disclosure relate to systems and techniques that may be used to infinitely control a speed of a zero-turn (“ZT”) vehicle, particularly a ZT lawnmower.
A ZT vehicle typically includes a frame and three or four wheels, such as one or two swiveling wheels mounted toward a front of the frame and two relatively large driving wheels at a rear of the frame. The driving wheels rotate independently of each other based on input from an operator. The operator can control the rotational speeds of the driving wheels via control levers, each associated with a respective driving wheel. Currently-available ZT vehicles, such as ZT lawnmowers, generally have only one speed-range, namely, the rotating speed of each driving wheel corresponds directly to a position of the respective control lever.
ZT vehicles, particularly ZT lawnmowers, may have different operating conditions. For example, a ZT lawnmower may have separate conditions for a grass cutting operation and a transportation operation: a lower speed-range is desired for a ZT lawnmower to get reliable control and better cutting result when cutting grass; and a higher speed-range is desired for the same ZT lawnmower to transport the vehicle more quickly and safely in between two job sites or back to a transport truck. However, one speed-range ZT vehicles do not satisfy this purpose.
Currently, there are two approaches dealing with the abovementioned issue. A first approach utilizes a pair of control levers that operate the lawnmower in a single wide speed-range from zero up to a high transport speed. A second approach provides a pair of levers that operate in a single speed-range, similar to the first solution, and a second lever/mechanism that can adjust an upper limit of the single speed-range.
The first approach allows for a larger or wider range of speed adjustment, but can lose resolution (precision) or lose control when operating at a lower cutting speed. The second approach allows for speed-range adjustments, but only between two predefined settings (e.g., high/low). In addition, the pair of control levers, as well as the speed-range adjustment lever, are all operated by hand, meaning the operator must let go of one lever to switch to the other. Therefore, the speed-range of the machine can't be safely adjusted “on the fly”, i.e., the machine must be stopped to adjust the speed-range.
In view of the foregoing reasons, it is desirable for a ZT lawnmower to have at least two different driving speed-ranges that can be adjusted “on the fly” by an operator.